1. Field of the Invention
The invention relates to a transmission and a power transmitting system, and in particular to a transmission having a rotating member and a support member that supports the rotating member such that the rotating member is not able to rotate, and a power transmitting system including the transmission.
2. Description of the Related Art
Generally, in a hybrid vehicle provided with a power transmitting system that transmits power from an internal combustion engine to driving wheels through engagement of gears, the internal combustion engine, a first motor generator, and a second motor generator connected to the driving wheels via a reduction gear are respectively connected to three rotating elements of a power distribution mechanism. In this type of hybrid vehicle, power of the second motor generator is transmitted to the driving wheels via the reduction gear, so that large power is generated while the size of the second motor generator is reduced.
A known example of the power transmitting system of the related art having the reduction gear is illustrated in FIG. 7 and FIG. 8. In FIG. 7 and FIG. 8, a second motor generator MG2 includes a stator (not shown) that forms a rotating magnetic field, and a rotor 1 disposed inside the stator and having a plurality of permanent magnets embedded therein.
A stator core of the stator of the second motor generator MG2 is formed by, for example, laminating magnetic steel sheets together, and is fixed to an inner circumferential wall of a case 2 as a support member of the power transmitting system.
The reduction gear is constructed such that a carrier as a rotating member that is one of rotating elements of a planetary gearset is fixed to the case 2, so as to reduce the speed of rotation of the second motor generator MG2. More specifically, the reduction gear includes a sun gear 3 coupled to a rotor shaft 1a formed integrally with the rotor 1, a ring gear 4 that transmits power to driveshafts (as an output portion) of driving wheels (not shown) via a gear mechanism, pinion gears 5 that mesh with the ring gear 4 and the sun gear 3 and transmit rotation of the sun gear 3 to the ring gear 4, and the carrier 6 as the rotating member that rotatably supports the pinion gears 5, as disclosed in, for example, Japanese Patent Application Publication No. 2005-308094 (JP-A-2005-308094). The ring gear 4 is formed integrally with a ring gear of a power distribution mechanism (not shown), and is operable to transmit power to the driveshafts when power of the internal combustion engine is transmitted to the ring gear of the power distribution mechanism.
Also, a plurality of protrusions 6a are formed at a radially outer portion of the carrier 6, and a plurality of recesses 2a are formed in the inner circumferential surface of the case 2. Through engagement of the protrusions 6a of the carrier 6 with the recesses 2a of the case 2, the carrier 6 is mounted in the case 2 such that the carrier 6 is not able to rotate relative to the case 2.
In the power transmitting system having the reduction gear as described above, power of the second motor generator MG2 is transmitted to the ring gear 4 via the sun gear 3 and the pinion gears 4, and then transmitted from the ring gear 4 to the driving wheels, so that the speed of rotation of the second motor generator MG2 (i.e., rotor 1) can be reduced by the reduction gear.
In the reduction gear as described above, however, the width of each of the recesses 2a is required to be larger than the width of each of the protrusions 6a, so that the carrier 6 can be reliably mounted in the case 2. As a result, gaps are formed between the protrusions 6a and the recesses 2a when the carrier 6 is mounted in the case 2.
With the gaps thus formed between the protrusions 6a and the recesses 2a, when torque variations of the internal combustion engine are transmitted from the ring gear 4 to the pinion gears 5, or when torque produced during rotation of the second motor generator MG2 in forward and reverse directions is transmitted to the pinion gears 5 via the sun gear 3, torque may be applied to the carrier 6 that supports the pinion gears 5. As a result, unpleasant sound or noise may occur due to collisions between the protrusions 6a of the carrier 6 and the walls of the recesses 2a of the case 2.